Media distribution continues to spread and evolve, e.g., because of the Internet. Many types of media, for example, journal articles, software, image data, and audio files, can be obtained through landline or wireless networks (including over the Internet). Yet it is still difficult for media users to obtain certain digital works, while it is also difficult for digital work owners to sell and control such works. For example, with a Google search, a list of references may be identified; however, many of those references will only be available (with the appropriate copyright clearance) if the user obtains and pays for a yearly subscription with a specific publisher. Having subscriptions with all necessary publishers is not practical.